1. Field of the Invention
Embodiments of the present invention generally relate to an integrated electron beam testing system for glass panel substrates.
2. Description of the Related Art
Active matrix liquid crystal displays (LCDs) are commonly used for applications such as computer and television monitors, cell phone displays, personal digital assistants (PDAs), and an increasing number of other devices. Generally, an active matrix LCD comprises two flat plates or panels having a layer of liquid crystal materials sandwiched therebetween. The flat plates are typically made of glass, a polymer, or other material suitable for having electronic devices formed thereon. One of the flat plates typically includes a conductive film disposed thereon and may be referred to as a color filter. The other flat plate typically includes an array of thin film transistors (TFTs), each coupled to a pixel. Each pixel is activated by addressing simultaneously an appropriate data line and gate line. Each TFT may be switched on or off to generate an electrical field between a TFT and a portion of the color filter. The electrical field changes the orientation of the liquid crystal material, creating a pattern on the LCD.
Because of the high pixel densities, the close proximity of the gate lines and data lines, and the complexity of forming the TFT's, there is a high probability of defects during the manufacturing process. Known testing methods for high density LCD panels include contact testing methodologies which require connection to and testing of each individual row/column intersection within the panel array. For such testing, advanced probing technology is necessary to establish reliable contacts among the densely populated pixel elements. A high density LCD array panel typically includes 640 by 480 pixels and a typical test time for such a panel is approximately 2 hours. For a color filter having the three primary colors, for example red, green and blue, a typical test cycle requires additional connections and requires additional testing time. The time and expense of testing, although necessary, may often be a limiting factor to the commercial success of large array LCD panels.
Prior art methods of detecting defects in the flat plate having the array of TFT's are limited to isolation of a particular area of the TFT array without ascertaining the precise location of the defect, which requires additional testing to accurately determine the position of a defect. Once the defect is localized accurately, the defect may be analyzed and repaired.
Therefore, a need exists in the art for a faster and more accurate testing method, which reduces the product costs of LCD panels.